*4.9. Fourier Transforms Infrared Spectroscopy (FT-IR)*

FTIR analysis of the SA–AG hydrogel-based films was performed by using an InfraRed Bruker Tensor 37, Ettlingen, Germany. The obtained spectrum was used to examine the functional groups and the interactions between film-forming components. The test was performed with an average of 32 scans, with a wavenumber range from 400 to 4000 cm−<sup>1</sup> .
